44 research outputs found
An algorithm to compare twoâdimensional footwear outsole images using maximum cliques and speededâup robust feature
Footwear examiners are tasked with comparing an outsole impression (Q) left at a crime scene with an impression (K) from a database or from the suspect\u27s shoe. We propose a method for comparing two shoe outsole impressions that relies on robust features (speededâup robust feature; SURF) on each impression and aligns them using a maximum clique (MC). After alignment, an algorithm we denote MCâCOMP is used to extract additional features that are then combined into a univariate similarity score using a random forest (RF). We use a database of shoe outsole impressions that includes images from two models of athletic shoes that were purchased new and then worn by study participants for about 6 months. The shoes share class characteristics such as outsole pattern and size, and thus the comparison is challenging. We find that the RF implemented on SURF outperforms other methods recently proposed in the literature in terms of classification precision. In more realistic scenarios where crime scene impressions may be degraded and smudged, the algorithm we proposeâdenoted MCâCOMPâSURFâshows the best classification performance by detecting unique features better than other methods. The algorithm can be implemented with the Râpackage shoeprintr
Natural Disaster and Risk of Psychiatric Disorders in Puerto Rican Children
We examined the persistence of psychiatric disorders at approximately 18 and 30Â months after a hurricane among a random sample of the child and adolescent population (4â17Â years) of Puerto Rico. Data were obtained from caretaker-child dyads (Nâ=â1,886) through in person interviews with primary caretakers (all children) and youth (11â17Â years) using the Diagnostic Interview Schedule for Children IV in Spanish. Logistic regressions, controlling for sociodemographic variables, were used to study the relation between disaster exposure and internalizing, externalizing, or any disorder. Childrenâs disaster-related distress manifested as internalizing disorders, rather than as externalizing disorders at 18Â months post-disaster. At 30Â months, there was no longer a significant difference in rates of disorder between hurricane-exposed and non-exposed youth. Results were similar across age ranges. Rates of specific internalizing disorders between exposed and unexposed children are provided. Research and clinical implications are discussed